Depends on what you want to do.
If you want to build your own stuff, it’s very different than selling on a hub.
So first, I’d say get your own goal. However if you own goal is to be in competition with other people on the forum, I guess you should take the advices with a huge rock of salt. Few people appreciate to hand you a loaded gun knowing you gonna shoot them.
Most important part is : money comes from trading. Basically you trade items, BUT you have a knowledge of the added price so the purchase cost of items is lower than if you were actually placing BOs from them.
Second part is : the more researched a BPO, the better. There are few cases where it’s not that important, eg when doing invention, but still.
Third part is : the cost from items you produce comes from
- the cost of the required items : minerals, etc. Basically the price you bought them on market +fees. This is reduced by placing BO, reprocessing ore, mining yourself, etc.
- the installation of the jobs. So if you manufacture in perimeter, it will cost like3 times more than in another adjacent system… This is reduced by going in a station/structure with lower couple index+tax. typically a NPC station is 1.1×index, a structure is (1+tax*0.01)×index×rigs
- the time cost : if a job takes 10days, it should have a part costing 10times more than a job that takes 1 day. This is reduced by using better TE, and going in a structure.
- the bpo cost, including the research. Research cost should be linear with the time to research. The return on bpos should be in years, so a bpo being used for eg 4 years straight should have its value added to the job.
- The volume you need to move. Same, this should be linear with the volume of the items you purchased and the volume of the items you sell. In many cases, the volume of the items you sell is higher, so you can use only this one. This is reduced by getting closer to your hub.
If you ignore any of those costs then you are making industry at a loss.